Electric lock



United States Patent 3,160,792 ELECTRIC LOCK Roger C. Brendeinuehi,Leslie H. Gerhardt, and Joseph B. Kriplre, Milwaukee, Wis, assignors toGeneral Motors Corporation, Detroit, Mich, a corporation of DelawareFiled Feb. 24, 1960, Ser. No. 10,721 Claims. (Cl. 317-134) Thisinvention pertains to locking devices, and particularly to an improvedelectric locking arrangement.

At the present time the majority of locking devices are of the multipletumbler type requiring a mechanical key for opening the same. Inasmuchas locks, of necessity, must be of reasonable size, the number oftumblers which can be embodied in a lock are limited, and accordinglythe number of different combinations are likewise limited. The presentinvention relates to an electric lock which, while comparable in size toconventional tumbler locks, has a substantially greater number ofavailable combinations. Accordingly, among our objects are the provisionof an electric lock of simplified design and construction; an electriclock having a large number of available combinations utilizing astandard circuit board; the further provision of an electric lockingcircuit including a plurality of series switches and a plu rality ofparallel switches; and the still further provision of a key for openingan electric lock of the aforesaid type.

The aforementioned and other objects are accompiished in the presentinvention by constructing the key to close the series switches and openthe parallel switches of the locking circuit. Specifically, the lockingcircuit includes a lock actuating solenoid, which when energized,permits the device with which the lock is associated to be operated inits intended manner. The locking circuit also includes a thwart relaywhich, when energized, open circuits the lock solenoid circuit.Moreover, if desired, the locking circuit may include an alarm whichwill be energized if a wrong key is inserted into the lock. The lock,per se, comprises a receptacle having a circuit board and a keyway witha plurality of leaf spring contacts disposed on opposite sides of thekeyway. The leaf spring contacts are electrically connected to a printedor etched circuit on the circuit board. In the instant lock, a singlecircuit board can be used for all of the available combinations therebygreatly simplifying the manufacturing technique. The individual circuitboard combinations are made by disconnecting certain conductors fromother conductors on each board which can be done by drilling through theetched or printed circuits.

The key may be composed of insulating material, or metal, having aplurality of pins projecting from both sides thereof. Externally, itcannot be determined whether the pins extend through the key or not. Thekeys are coded by extending some of the pins through the key body toform connected contact pairs and separating other of the pins by aninsulator in the key body to form disconnected contact pairs. Thethrough pins are used to close the series switches, and the open pinsare used to open circuit the parallel switches.

Since it is desirable to have all of the keys fully insorted in thereceptacle to energize the circuit, either of the two end contact pairsmust close a series switch. Accordingly, there are three differentcombinations of the first two contact pairs, namely contact pair oneclosed, contact pair two open; contact pair two closed, contact pair oneopen; and contact pairs one and two closed. The remaining switches maybe either open or closed, so that there are two different combinationsfor each switch. A typical key of standard size can conveniently carrysixteen pairs of contacts so that with this type of lock there is apossibility of 49,151 useful combinations.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred embodiment is clearly shown, and whereinsimilar numerals depict similar parts throughout the sev eral views.

In the drawings:

FIGURE 1 is a transverse sectional view of a typical key receptacle.

FIGURE 2 is a plan view of a typical circuit board.

FIGURE 3 is a fragmentary view in elevation of a typical key.

FEGURE 4 is a perspective view of one of the leaf spring contacts usedin the receptacle.

FIGURE 5 is a diagram of the locking circuit.

With particular reference to FIGURE 1, the lock includes a receptacle 1%comprising a housing 12 of insulatin material having a keyway 14, and acircuit board 16 suitably attached to one side of the housing 12. Thecircuit board includes a base of insulating material, and has a circuit18, either etched or printed on one side. The keyway 14 has alongitudinally extending tongue 26 extending thereinto, the tongue 29being adapted for reception in a longitudinally extending groove 22 of akey 24 for guiding and properly aligning the key within the keyway 14.

With reference to FIGURE 2, the printed or etched circuit 18 on thecircuit board 16 comprises one longitudinaliy extending conductor 26,four longitudinally extending buss bar conductors 2%, 3t 32. and 34, andthirty-five transversely extending conductors 36, 38, etc., through 194.Each of the transverse conductors 42 through 104 has a ieaf springcontact electrically connected thereto, 42a, 44a, etc, through 1164a.The transverse conductors are arranged in two rows, as depicted inFIGURE 2. The ends of conductors 42 through 72 are connected in parallelbetween buss bars 28 and 3'9, with the ends of conductors 74- through104 connected in parallel between buss bars 32 and 34-.

A typical leaf spring contact is shown in FIGURE 4, and comprises aterminal portion 1%, which is electrically connected to its respectiveconductor in the circuit board 16, and a contact portion Hi3. As seenparticularly in FIGURE 1, the contact portions of the leaf spring contacts are disposed in the keyway 14 in four rows, two rows on each sideof the keyway. Each row includes eight contacts so that the receptacle12 contains thirtytwo leaf spring contacts. The contacts are preformedas depicted in FIGURE 4- and suitably held in position in a mold whilethe housing 12 is molded therearound so that the contacts are integrallysupported within the housing.

As alluded to hereinbefore, the same circuit board can be used for alllocks. In order to code the locks, individual circuit combinations aremade by disconnecting certain conductors from each other and/ or formthe buss bars and this can be accomplished by drilling through theconductor and/ or buss bar and board as depicted by the holes in FIGURE3. The conductors 26, 36, 38, 4t) and 42 have terminals 26b, 36b, 38b,40b and 42b electrically connected thereto. The terminals 38b and 4012are connected by suitable wires to opposite sides of a solenoid operatedlock actuating means. In addition, in the specified circuit boarddepicted in FIGURE 2 the conductors 52 and 56 have terminals 52b and 56belectrically connected thereto, which terminals are connected byexternal wires 112 and 114 respectively, to terminals 38b and 46b,respectively. The terminals 26b and 4212 are connected to a powersource, and the terminal 36b is connected to thwart means to bedescribed.

With reference to FIGURE 3, the key 24 may have either a metal key bodyor a plastic insulator body. However, as shown, the key 24 includes ametallic body. The keyway has rows of spaced pins located on oppositesides of the slot, or groove, 22. Each row comprises eight pins, so thatthe key includes sixteen pins 116, 118, etc., through 146. Each of thepins 116 through 146 constitutes a pair of contacts which are engageablewith a pair of the contacts 42a through 1114a carried by the receptacie12. All of the pins 116 through 146 have the same exterior appearance onthe key 24. However, as seen in FIGURE 1, some of the pins extendthrough the key body, while other of the pins are spaced apart by aninsulator, whereby coding the key for a particular coded circuit board.

When the body of the key 24 is metallic, pins 116 through 146 aremounted in strips of plastic insulating material 148 and 150. The pinshown in the upper strip 143 in FIGURE 1 is separated by a portion ofthe insulator strip 143 and is thus nonconductive. The pin depicted inthe lower strip 158 in FIGURE 1 is continuous and is thereforeconductive. Consequently, the switch constituted by the leaf springcontacts in engagement with the lower pin in FIGURE 1, is closed, whilethe switch constituted by the leaf spring contacts associated with theupper pin in the key in FIGURE 1, is open.

As alluded to hereinbefore, a properly coded key is constructed to closeseries switches and open parallel switches when inserted in a receptaclehaving a circuit of the same code. With reference to FIGURE 5, a typicalcircuit will be described. A battery 15?. has one terminal connected toground and the other terminal connected through a thermal overloadcircuit breaker 154 to a wire 156. The wire 156 is connected to terminal425 of the circuit board 16. The circuit board 16 depicted schematicallyin FIGURE is coded like the circuit board shown in FIGURE 2.Accordingly, the series switches which must be closed to energize thelock actuating means include contact pins 116, 132, 118, 136, 138, 126,128 and 144. When the key is fully inserted, contact pin 116 bridgescontacts 42a and 74a, contact pin bridges contacts 44a and 76a; contactpin 118 bridges contacts 46a and 78a; contact pin 13dbridges contacts48a and 80a; contact pin 120 bridges contacts 50a and 82a; contact pin136 bridges contacts 52:: and 84m; contact pin 122 bridges contacts 54aand Sea; contact pin 138 bridges contacts 564: and 88a; contact pin 124bridges contacts 58a and 99a; contact pin 14!) bridges contacts 611a and12a; contact pin 126 bridges contacts 62a and 94a; contact pin 14-2bridges contacts 64!: and 95a; contact pin 12 5 bridges contacts 66a and98a; contact pin 144 bridges contacts 68a and 100a; contact pin 13%bridges contacts 743a and 102a; and contact pin 146 bridges contacts 72aand 104a. In the specifically disclosed locking circuit, pins 120, 122,12 i, 1341, 134 141i, 142 and 146 are nonconductive so as to open theparallel switches. A lock solenoid 158, constituting the lock actuatingmeans, is con nected between terminals 38!: and 41111, and a thwartrelay 160 is connected between terminals 361) and 26b. The thwart relay160, when energized, opens a switch 162 which open-circuits the the locksolenoid S irrespective of closure of the series switches.

The circuit depicted in FIGURE 5 also includes an alarm systemcomprising a vehicle horn 164. The horn is controlled by a horn relay166, one terminal of which is connected to ground and the other terminalof which is connected to the conductor 319 by wire 16%. The horn relay166, of course, can be actuated manually by a horn switch 170 whichcompletes the circuit to the horn relay through wire 172.

When a properly coded key is inserted into the receptacle 10 having thecircuit board 16 depicted in FIGURE 2 and schematically depicted inFIGURE 5, the series switches comprised by key pins 116, 132, 118, 136,138, 126, 128 and 144 will connect the lock solenoid 158 to oppositesides of the battery 152 thereby energizing the same. All of theparallel switches formed by contact pins 13 i, 120, 122, 124, 140, 142,130 and 146 remain open so that the thwart relay 160 is deenergized asis the alarm circuit. In order to prevent energization of the locksolenoid 158 by supplying power to only one terminal of the locksolenoid, the series switches are arranged on both the power and groundsides of the lock solenoid.

The circuit breaker 154 is included in the locking circuit to deenergizethe circuit, if an all metal key is inserted in the receptacle, whichmetal key would short circuit the battery 152. With the key receptacledesigned as shown and described, the locking circuit cannot be energizeduntil the key is fully inserted in the receptacle. Accordingly, eitherof the two end switches formed by the contact pins 116 and 132 on thekey must be closed. Accordingly, there is a possibility of threedifferent switch combinations of the contact pins 116 and 132. Theremaining switches may be either open or closed, thus giving twocombinations for each switch. Since the circuit board disclosed has atotal of sixteen switches the total number of combinations would be theproduct of 3 2 However, since one of these combinations would have allof the remaining switches open, there are c-niy (3 2 )1 useablecombinations. This is true since at least two switches should be used inseries with the lock solenoid to prevent picking of the lock. Thus, witha sixteen switch circuit board such as disclosed, there would be 49,151useful combinations. If an improperly coded key is inserted into thereceptacle, the lock solenoid 158 will not be energized. Moreover, insome instances it may energize the alarm 164 by closing one of theparallel switches.

While the embodiment of the invention as herein disclosed constitutes apreferred form, it is to be understood that other forms might beadopted.

What is claimed is as follows:

1. An electric lock including, a receptacle having a keyway and aplurality of spaced stationary switch contacts insulated from each otherand extending into said keyway, said contacts being arranged in alignedpairs with one contact of each pair being on opposite sides of saidkeyway, a circuit board having a conductor electrically connected toeach receptacle carried contact, said conductors being coded byselective electrical interconnection of at least some of said conductorswith other of said conductors on said board to form an unlockingcircuit, and a key insertable into said keyway and having a plurality ofspaced switch contacts insulated from each other, the number of keycarried contacts being equal to the number of receptacle carriedcontacts, half of said key carried contacts being located on each faceof said key so that each key carried contact is engageable with areceptacle carried contact, said key carried contacts being coded byselective electrical interconnection of at least some of said keycarried contacts with other of said key carried contacts so that only aproperly coded key will complete the unlocking circuit when insertedinto the keyway of said receptacle.

2. An electric lock including a receptacle having a keyway and aplurality of spaced stationary switch contacts insulated from each otherand extending into said keyway, said contacts being arranged in alignedpairs with one contact of each pair being on opposite sides of saidkeyway, a circuit board having a conductor electrically connected toeach receptacle carried contact, said conductors being coded byselective electrical interconnection of at least some of said conductorswith other of said conductors on said board to form an unlockingcircuit, and a key insertable into said keyway and having a plurality ofspaced switch contacts insulated from each other, the number of keycarried contacts being equal to the num ber of receptacle carriedcontacts, half of said key carried contacts being located on each faceof said key so that each key carried contact is engageable with areceptacle carried contact, said key carried contacts being coded byselective electrical interconnection of at least some of the key carriedcontacts on opposite faces of the key to form bridging means engageablewith the pairs of receptacle carried contacts on opposite sides of saidkeyway so that only a properly coded key will complete the unlockingcircuit when inserted into the keyway of said receptacle.

3. The electric lock set forth in claim 2 wherein said receptaclecarried switch contacts comprise leaf springs.

4. The electric lock set forth in claim 2 wherein said circuit board iscomposed of insulating material having conductors thereon.

5. The electric lock set forth in claim 4- wherein at least some of theconductors on said board are disconnected from other conductors by holesthrough said board and the conductors.

6. The electric lock set forth in claim 2 wherein said key carriedcontacts comprise pins, at least some of which extend through said keyto form electrically interconnected pairs of contacts and others ofwhich are insulated from each other to form insulated pairs of contacts.

7. An electric locking arrangement including, actuating means movablebetween lock open position when energized and lock closed position whendeenergized, a source of power for energizing said lock actuating means,at least one switch connected in series between one side of said powersource and one side of said lock actuating means, at least one switchconnected in series between the other side of said power source and theother side of said lock actuating means, coded switch operating keymeans for closing said series switches to energize said lock actuatingmeans, and thwart means connected in circuit with said lock actuatingmeans, said thwart means, when actuated, precluding energization of saidlock actuating means irrespective of the closure of said seriesswitches.

8. An electric locking arrangement including, lock actuating meansmovable between lock open position when energized and lock closedposition when deenergized, a source of power for energizing said lockactuating means, at least one switch connected in series between oneside of said power source and one side of said lock actuating means, atleast one switch connected in series between the other side of saidpower source and the other side of said lock actuating means, codedswitch operating key means for closing said series switches to energizesaid lock actuating means, thwart means connected in circuit with saidlock actuating means, said thwart means, when actuated, precludingenergization of said loclr actuating means irrespective of the closureof said series switches, thwart actuating means, and at least one switchconnected in parallel with said series switches between said powersource and said thwart actuating means and closable by an improperlycoded switch operating key means for energizing said thwart actuatingmeans.

9. An electric locking arrangement including, lock actuating meansmovable between lock open position when energized and lock closedposition when deenergized, a source of power for energizing said lockactuating means, a plurality of series switches connected between saidlock actuating means and said power source, thwart means connected incircuit with said lock actuating means, thwart actuating means, aplurality of parallel switches connected in parallel with said pluralityof series switches between said thwart actuating means and said powersource, and coded switch operating key means for closing said seriesswitches and opening said parallel switches to energize said lockactuating means. 1

10. The electric locking arrangement set forth in claim 9 wherein saidthwart means comprises a switch connected in series with said lockactuating means and wherein said thwart actuating means comprises arelay for operating said switch, said relay being connected to saidpower source upon closure of any one of said plurality of parallelswitches.

Reterenc s fitted in the file of this patent UNITED STATES PATENTS1,393,822 Parker Oct. 18, 1921 1,695,518 Watson Dec. 18, 1928 2,436,809Joel Mar. 2, 1948 2,473,664 Taylor June 21, 1949 2,613,252 Heibel Oct.7, 1952 2,985,709 Mammola May 23, 1961

7. AN ELECTRIC LOCKING ARRANGEMENT INCLUDING, ACTUATING MEANS MOVABLEBETWEEN LOCK OPEN POSITION WHEN ENERGIZED AND LOCK CLOSED POSITION WHENDEENERGIZED, A SOURCE OF POWER FOR ENERGIZING SAID LOCK ACTUATING MEANS,AT LEAST ONE SWITCH CONNECTED IN SERIES BETWEEN ONE SIDE OF SAID POWERSOURCE AND ONE SIDE OF SAID LOCK ACTUATING MEANS, AT LEAST ONE SWITCHCONNECTED IN SERIES BETWEEN THE OTHER SIDE OF SAID POWER SOURCE AND THEOTHER SIDE OF SAID LOCK ACTUATING MEANS, CODED SWITCH OPERATING KEYMEANS FOR CLOSING SAID SERIES SWITCHES TO ENERGIZE SAID LOCK ACTUATINGMEANS, THWART MEANS CONNECTED IN CIRCUIT WITH SAID LOCK ACTUATING MEANS,SAID THWART MEANS, WHEN ACTUATED, PRECLUDING ENERGIZATION OF SAID LOCKACTUATING MEANS IRRESPECTIVE OF THE CLOSURE OF SAID SERIES SWITCHES.